1. Field of the Invention
The present invention relates to a method and apparatus for magnetic resonance imaging, and in particular to a method and apparatus for magnetic resonance imaging of the coronary arteries.
2. Description of the Prior Art
A study by Kim et al. entitled “Coronary Magnetic Resonance Angiography for the Detection of Coronary Stenoses,” New England Journal of Medicine (2001), Vol. 345, No. 26, pages 1863-1869 showed that coronary artery magnetic resonance angiography (MRA) may be a viable diagnostic alternative to selective x-ray catheter-based angiography. The detection of coronary artery stenoses using MRA may be improved by viewing the entire artery as a whole, so as to prevent a torturous segment of the artery from mimicking a stenosis, and thus causing a misdiagnosis, as reported in “Whole-Heart Steady-State Free Precession Coronary Artery Magnetic Resonance Angiography,” Weber et al., Magnetic Resonance in Medicine, Vol. 50 (2003), pages 1223-1228.
Coronary artery datasets often are evaluated either in cine mode or are reformatted using various image processing tools designed to remove the signal produced by adjacent tissue. Example of such techniques are described in “‘Soap-Bubble’ Visualization and Quantitative Analysis of 3D Coronary Magnetic Resonance Angiograms,” Etienne et al., Magnetic Resonance in Medicine, Vol. 48, No. 4 (2002), pages 658-666 and “Coronary Artery Imaging Using Contrast-Enhanced 3D Segmented EPI,” Deshpande et al., Journal of Magnetic Resonance Imaging, Vol. 13, No. 5 (2001), pages 676-681. Because of the strong signal produced by nearby cardiac chambers and the tortuous path of coronary arteries, such procedures can be time consuming, and there efficacy often is heavily dependent on user training. This is true even for contrast-enhanced 3D coronary MRA, when adjacent tissue often is dramatically suppressed by magnetization preparation, as described in “Coronary Arteries: Magnetization-Prepared Contrast-Enhanced Three-Dimensional Volume-Targeted Breath-Hold MR Angiography,” Li et al., Radiology, Vol. 1019, No. 1 (2001), pages 270-277